Monday, December 31, 2012

Last January I wrote about Surfbird behavior in high pools along the rocky shore. In that case, two Surfbirds were facing off, both expressing interest in using the pool to bathe. Today I encountered similar behavior, but this time between a Surfbird and Black Turnstone. And I was lucky enough to record a few Surfbird vocalizations during the interaction.

First the pictures. Here's a visualization of the behavior. I think you'll be able to tell that both birds were pretty invested in defending the pool!

And here are two images of Surfbirds bathing in high pools:

After taking a bath, the birds roosted on nearby rocks. For comparison, the Surfbird is on the left and the Black Turnstone is on the right:

And now for the recordings. Below are three short recordings of the Surfbird vocalizing. There are large waves breaking in the background, but listen for the high-pitched squeals. (You may need to turn up the volume.)

I can't find much information about Surfbird calls during the non-breeding season, so this is an opportunity to document what they sound like during the winter while defending a bathing site. (For the record, this is the individual on the left in the first two photos.)

Here's hoping for a year full of new and interesting natural history observations!

Saturday, December 29, 2012

A quick walk at low tide on Doran Beach on 28 December 2012 led to sightings of these signs and trails in the sand. Can you guess who made them?

We dug down into the sand underneath the raised portions and found these beautiful snails. Most of the snails we encountered were ~1-2 cm long.

Purple Olive Snails, Callianax biplicata (formerly Olivella biplicata), are elongate snails with very smooth, polished shells. They're often olive green in color, with purple near the bottom of the shell. But some individuals are very pale and others are dark purple (see below).

Here's a better view of the underside of the shell, highlighting the purple coloration and the shell aperture (opening) that is very long and narrow. Note also the shallow notch at the end of the shell through which the snail can extend a siphon.

Some of the snails were crawling along the surface of the sand. The foot and mantle extend forward and upward like a plow. In the photo below, the foot/mantle are on the left and the short spire at the tip of the shell is on the right.

Purple Olive Snails display predator avoidance strategies when disturbed. They rise up and somersault to move away from potential predators such as sea stars (e.g., Pisaster brevispinus). In the next image you can see a snail in this unusual position with its large foot flared out on the right side. (In this case, the snail was responding to human contact.)

Although sandy beaches can be challenging places for animals to live, this species can be found in intertidal areas on wave-protected sandy beaches along the Pacific Coast from British Columbia to Baja California (and subtidally on wave-exposed coasts).

Friday, December 28, 2012

This is a follow-up to last night's post. In that entry, I included images of adult Mew Gulls. Here are a few photos showing immature Mew Gulls.Gull plumages can be confusing. It takes gulls between 2-4 years to attain adult plumage (the timing depends on the species). During the first few years, their appearance changes dramatically. They usually start out mottled brown/gray and gradually become grayer above and whiter below. The color patterns on their wings and tails also change, as do their bill and leg colors.

So instead of learning what *a* Mew Gull looks like, you need to learn at least 3 or 4 different plumages (e.g., juvenile, first-year, second-year, adult).

Here's a picture showing an adult Mew Gull in the foreground and a second-year Mew Gull in the background. Can you see differences between these two individuals?

In the second-year bird (in the background above):

- the head and neck are more heavily mottled with gray

- the bill and legs are more gray/green than yellow (see legs in photo below)

- the black primary feathers (wing tips) lack the large white spots and instead show very narrow pale edges

- the tertial feathers show black markings [Tertial feathers are actually elongated inner secondary feathers located where the trailing edge of the wing meets the body. In these images, the tertials have broad white tips and are visible between the gray back/upper wing and the black wing tips.]

- the tail has black markings (not that visible in these birds, but adults have all white tails)

Here's another view of the second-year Mew Gull. Look for all of the characteristics listed above:

If you'd like to quiz yourself, here are two more images (below). Can you tell which is the adult and which is the second-year bird?

Answer: The first photo shows a second-year Mew Gull, the second image is an adult Mew Gull.

Thursday, December 27, 2012

I took these photos at Doran Beach on 15 December 2012, but haven't had a chance to post them until now. Do you recognize this gull?

Mew Gulls (Larus canus) are relatively small gulls with long wings. Note the rounded head, short and slender bill, and relatively large, dark eye.

The color of the bill and legs varies from gray-green to green-yellow. Here's an individual on the gray-green end of the spectrum.

The next image shows the range in leg color between two birds standing next to each other. Also note how the shape of the head can look different depending on whether the neck is extended or pulled in.

Fourteen species of gulls have been documented on Bodega Head (for this number, I'm only including species with "gull" in their common name). Ring-billed Gulls (Larus delawarensis) can look somewhat similar to Mew Gulls, but side-by-side it's easy to pick out some of the differences.

In the next two pictures, compare the following:

- overall appearance (Mew Gulls are more delicate)

- bill (Ring-billed Gulls have a more robust bill with an obvious black ring near the tip of the bill)

- mantle or back color (Mew Gulls are slightly darker gray)

- white spots on primary feathers (Mew Gulls show larger white spots)

- tertial crescent (the white "patch" between the gray back and black wing tips; it's wider and more obvious in Mew Gulls)

Mew Gulls winter along the Pacific Coast, so you can see them in the Bodega Bay area from
fall through spring (most depart by the end of April, heading north to
breed in northwest Canada and Alaska).

Monday, December 24, 2012

Sunday, December 23, 2012

I really like chickadees, but they're tough to photograph! They're small, always on the move, and often hidden behind branches or leaves (at least whenever I try to take a picture of them).

The Black-capped Chickadee (Poecile atricapillus) pictured above was photographed near Rexhame Beach in Massachusetts on 23 December 2012.

After living in California for 8 years, and spending time with Chestnut-backed Chickadees (Poecile rufescens), I'm struck by the size difference between the two species.

Chestnut-backed Chickadees are the smallest of the 7 species of chickadees in North America. They range from ~100-120 mm long, while Black-capped Chickadees measure ~123-145 mm long.

I still don't have great photos of Chestnut-backed Chickadees, but here are couple from Bodega Bay (below). In the first image you can just barely see a hint of the chestnut color, but the second image shows off the chestnut on the back and along the sides. (Compare this with the gray on the back of the Black-capped Chickadee above.)

Are you curious about the other 5 species of chickadees? They include Boreal, Carolina, Gray-headed, Mexican, and Mountain chickadees.

Here's a little quiz —
In which state can you see 5 species of chickadees? (The answer is at the bottom of this post.)

Whichever species you encounter, it's always fun to watch these bright-eyed and energetic songbirds.

P.S. Answer to quiz above: Alaska! The five species of chickadees in Alaska include Black-capped, Boreal, Chestnut-backed, Gray-headed, and Mountain.

Saturday, December 22, 2012

Common Redpolls (Acanthis flammea) are primarily northern birds, spending most of their time in Canada and Alaska. When their food sources are limited in the north, they move further south. They are rare in northern California, but show up more regularly in New England (where I'm writing from tonight).

I love their ruby red "polls" or "caps." Note also the small yellow bill (with dusky tip), black around the base of the bill, and overall brown/gray/white streaking. Adult males have a pinkish or rose color on their breasts and flanks (stronger during the breeding season), while young males and females have mostly white breasts.

Redpolls are primarily seed eaters. In the dunes this morning they were interested in the seeds of goldenrod (photo above) and wormwood (very first photo).

This was a large flock of birds (more than 100) and sometimes they would swirl around above the vegetation and then descend in a tight group to a seed source.

Here are two images of redpolls searching for seeds —
the first while clinging to goldenrod, the second while walking along the sand.

I was amazed at how quickly they could disappear among the vegetation. But this pictures shows how well the streaking on their backs blends in with a background of grass blades.

An interesting note —
Redpolls generally
have a shallow notch at the tip of their tails. Today, some of these
birds displayed very deep notches (similar to a Barn Swallow). In
reviewing the pictures, I think the birds with deeply notched tails were molting their central tail feathers (see below).

One more redpoll fact: To survive very cold temperatures, redpolls have special internal seed storage pouches along their esophagus. They can store seeds there and then eat them later —
very helpful on a night like tonight! Brrrrr!

Thursday, December 20, 2012

It's been a good fall for seeing this hawk in Sonoma County. Although distant, it seemed worth posting these pictures, in hopes that other people will keep an eye out for this handsome raptor.

Ferruginous Hawks (Buteo regalis) prefer open habitats such as grasslands. They're known for eating jackrabbits, which are available along Coleman Valley Road where these pictures were taken (on 19 December 2012).

There are several features to look for:

- large size (bigger than a Red-tailed Hawk)

- mostly white below (paler than most other hawks in this area)

- rufous coloration on the back, shoulders, and leg feathers (hence the name "ferruginous" which means "rusty")

- black markings at the "wrist" or bend of the wing

- wide gape (the corner of the mouth extends beyond the eye)

- white or gray tail

- wavy, rust-colored bars on the belly

Here are two pictures showing some of the wing patterning:

And a few more of the same bird perched high in a tree. Look for the rusty bars on the belly.

The bright light on the hawk's pale belly made photographing this bird a little challenging. Later I was intrigued to read this description in the Birds of North America account (Bechard and Schmutz 1995):

"White belly of light morph reflects sun and makes hawk
highly visible even when roosting on ground. This could be an advantage for
advertisement in a territorial or mating context in open landscape."

Note that there are two forms of Ferruginous Hawks, light morphs (shown above) and dark morphs. The dark morphs are much less common, making up 0-10% of populations. In November, a dark morph individual was observed in Petaluma (along Adobe Road), but I haven't heard if it's still around.

Wednesday, December 19, 2012

I know some people will think I'm crazy, but I'm always excited when there's a chance of seeing frost here. It's not as common on the coast, but here are a few pictures from several fence posts between Sebastopol and Bodega Bay.

The frost crystals were very long, making these lichens look like miniature trees!

The next photo shows a variety of crystals that formed on a small clump of moss.

And one more, showing sparkling crystals on a crustose lichen.

All of these images were taken in a field next to a stream in a low-lying valley on 19 December 2012.

I think the last time we had snow was in 2005. I still dream about sledding and snowball fights, but for now I'll thank Jack Frost for providing wonderful views of winter wonderlands. (Now if only I could shrink down to walk among the tiny crystalline trees!)